1. Field of the Invention
The present invention relates to a sucrose intermediate. More particularly, the present invention relates to sucrose intermediates having the structure: ##STR1## wherein X is selected from the group consisting of chlorine, bromine and iodine. In a preferred embodiment of the present invention, the compound of structure (I) is 6,6'-dichloro-6,6'-dideoxy-1',2,3,3',4,4'-hexa-O-methylsucrose and is useful as an intermediate in the synthesis of other difunctional monomers. Compound (I) may also be used as a monomer for the preparation of novel water-absorbent polyethers.
2. Description of the Prior Art
In the past, many attempts have been made to employ carbohydrates for the development of well-characterized novel polymers of some practical significance. The use of sugars and their derivatives in the production of polymers is of growing interest since polymers containing mono- or disaccharides in their main chain or as grafted pendant groups or chains display useful and unique properties such as hydrophilicity, chirality, biological activity, biodegradability, and the like. Furthermore, most sugars are available at economical prices and are industrially produced in large quantities by cultivation in plants and microorganisms, followed by chemical isolation or by degradation of plant waste material followed by isolation. For instance, sucrose is produced on a scale that is larger than any other pure organic chemical, world-wide.
The major problem associated with the use of carbohydrates for developing polymers is the similar reactivity of the primary and secondary hydroxyl groups on the carbohydrate moiety. Hence, when carbohydrates are polymerized non-enzymatically with other monomers, the resulting polymer products are often a mixture of linear, cross-linked and branched chain products. This is due to the reaction of both the primary and secondary hydroxyl groups in the carbohydrate moiety with electrophilic groups in the other monomer.
Many attempts have been made in the past towards polymerizing carbohydrates such as those attempts described by N. Ogata et al in J. Polym. Sci., Polym. Chem. Ed., Vol. 19, p. 2609 (1981) and Vol. 22, p. 739 (1984); and S. K. Dirlikov, "Monomers and Polymers Based on Mono and Disaccharides", Pacific Polymer Preprints, First Pacific Polymer Conference, Dec. 12-15, 1989, Volume 1, pp. 113-114.
Although Dirlikov, supra, claims that high molecular weight polymers have been made, no proof has been shown that these polymers are strictly linear and do not contain additional cross-linked or branched chain polymers and that only the primary hydroxyl groups react thereby forming a strictly linear polymer.
Sucrose used as a starting carbohydrate for the production of carbohydrate polymers would be ideal since it is produced in vast quantities and is low in price. To synthesize intermediate sucrose derivatives for further use in the production of novel polymers using sucrose as a starting compound is difficult due to the reactivity of the primary hydroxyl groups at carbons 6, 1' and 6' and the remaining five secondary hydroxyl groups.
Several sucrose derivatives used as intermediates in the preparation of a variety of products have been previously described. For instance, U.S. Pat. No. 4,117,224 relates to the preparation of 6,6'-dichloro-6,6'-dideoxysucrose and 1',6,6'-trichloro-1',6,6'-trideoxysucrose. These intermediates can be used in the preparation of the corresponding anhydro, azido and amino derivatives which can be used to make various resins.
Sweetening compounds of 4,1',6'-trichloro-4,1',6'-trideoxygalactosucrose are described in U.S.Pat. No. 4,612,373. The alkyl and ether derivatives are also described and these sucrose derivatives are about 400 times sweeter than sucrose.
Whistler et al in Methods in Carbohydrate Chemistry, VIII, 227 (1980) describes the synthesis of 6,6'-dichloro-6,6'dideoxysucrose. Although this is a known compound, it is difficult to use 6,6'-dichloro-6,6'-dideoxysucrose as an intermediate in the preparation of various methylated derivatives due to its structure. It is also not possible to use this compound as a monomer in the development of linear polyethers by Williamson ether synthesis.
It has now surprisingly been discovered that the compound of structure (I) wherein X is selected from the group consisting of chlorine, bromine and iodine and the preferred embodiment, namely 6,6'-dichloro-6,6'-dideoxy-1',2,3,3',4,4'-hexa-O-methylsucrose can be used as key intermediates in the preparation of other difunctional monomers, as well as monomers for preparing novel water-absorbent polyethers.